The fridge-sized robotic lab, which landed on a comet called 67P/Churyumov-Gerasimenko in November in an historic first, last made contact via the Rosetta orbiter on July 9.
The lander initially bounced away from its intended landing place upon reaching the comet and settled in the shadows where there was not enough sunlight to power its solar panels.
But with the comet approaching the sun, Philae woke up last month, stirring hopes that more information could be gleaned from the surface of comet using the lander's drilling and measuring tools.
Scientists said last week they fear the lander may have shifted position again, hampering communication efforts.
"In the telemetry received, we have observed signs that Philae could have moved and that its antennas are thus perhaps more concealed or their orientation might have changed," said project leader Stephan Ulamec of the German Aerospace Center (DLR). The data also indicated one of Philae's two transmission units appeared not to be working properly, and a receiver was damaged
Attempts to contact Philae will now take a break for two weeks while Rosetta explores the southern side of the comet with its own instruments, Koen Geurts from the lander control team at the DLR German Aerospace Center said in a video message.
"In about two weeks, Rosetta will be flying back north again and communication could be possible," Geurts said.
Written with agency inputs